How muscles grow after a workout?

After you workout, your body repairs or replaces damaged muscle fibers through a cellular process where it fuses muscle fibers together to form new muscle protein strands or myofibrils. These repaired myofibrils increase in thickness and number to create muscle hypertrophy (growth). 1 Muscle growth occurs whenever the rate of muscle protein synthesis is greater than the rate of muscle protein breakdown. read more

In the book “Sport Nutrition for Health and Performance,” Melinda Manore et. al. describe the anabolic phase as the 45-minute period after your workout when your muscles go into overdrive to repair the damage from weight lifting. read more

Your muscles start to change almost immediately after a strength-training session, but you won't notice those changes for several weeks or even months. Len Kravitz, program coordinator of exercise science at the University of New Mexico in Albuquerque, notes that protein synthesis -- the process by which muscles grow bigger and stronger -- occurs within two to four hours after a workout. read more